The California Unified Cycle (UC) is a dynamometer driving schedule for light-duty vehicles developed by the California Air Resources Board. This test is also referred to as the Unified Cycle Driving Schedule (UCDS). The UC test was referred to in the past as the LA92 test. It was often called the “Unified LA92”, to distinguish it from a “short LA92” test, which included the first 969 seconds of the Unified LA92.
The UC test has a similar three-bag structure, but is a more aggressive driving cycle than the federal FTP75; it has higher speed, higher acceleration, fewer stops per mile, and less idle time. Vehicles tested over the UC typically produce higher emissions compared to vehicles tested over the FTP.
One of the applications of the UC cycle is testing of vehicles fitted with direct ozone reduction technologies (the Supplemental Federal Test Procedure, SFTP, was used for that purpose earlier).
The UC test, Figure 1, is a three-bag test run in the following manner: Bags 1 and 2 are run consecutively, followed by a ten minute hot soak, then Bag 3 which is a duplicate of Bag 1. Overall cycle emissions are calculated in the same manner as the weighted, overall FTP-75 formula, taking actual mileage from the UC into account.
The following are some characteristic parameters of the cycle:
- Unified Cycle:
- Duration: 1435 seconds
- Total distance: 9.8 miles (15.7 km)
- Average Speed: 24.6 mi/h (39.6 km/h)
- Bag 1:
- Duration: 300 seconds
- Total distance: 1.2 miles (1.9 km)
- Bag 2:
- Duration: 1135 seconds
- Total distance: 8.6 miles (13.8 km)